The connection to adb is down, and a severe error has occure

1. error: build failedd: \ workspace \ ganji \ build. xml: 144: The following error occurred while executing this line: D: \ workspace \ ganji \ build. xml: 271: Unable to delete file D: \ workspace \ ganji \ tmp \ proguard \ tmp. jar solution: a simulator has been opened and cannot be re-compiled. You must disable one. 2. error: The connection to adb is down, and a severe error has occured. solution: run cmd to the directory adb kill-server in the sdk tools file, and then select adb start-server or right-click the Project --> Android Tools --> Fix Project Properties, and then run. 3. error: The connection to adb is down, and a severe error has occured. [09:36:56-HelloOPone] You must restart adb and Eclipse. [09:36:56-HelloOPone] Please ensure that adb is correctly located at 'd: \ OPhoneSDK_1.5 \ platform-tools \ adb.exe 'and can be executed. solution: method 1. run adb kill-server in cmd, and then use adb -startserver1_2.20.1then kill adb.exe in the task manager, and then restart Eclipse. Method 3. if methods 1 and 2 do not work, check that adb.exe exists in the last sentence: platform-tools( or there is no platform-tools Folder under the relevant path. If not, choose to create a new folder, and copy all the files in tools to platform-tools)